Genome-wide identification of gene expression in contrasting maize inbred lines under field drought conditions reveals the significance of transcription factors in drought tolerance

Drought is a major threat to maize growth and production. Understanding the molecular regulation network of drought tolerance in maize is of great importance. In this study, two maize inbred lines with contrasting drought tolerance were tested in the field under natural soil drought and well-watered conditions. In addition, the transcriptomes of their leaves was analyzed by RNA-Seq. In total, 555 and 2,558 genes were detected to specifically respond to drought in the tolerant and the sensitive line, respectively, with a more positive regulation tendency in the tolerant genotype. Furthermore, 4,700, 4,748, 4,403 and 4,288 genes showed differential expression between the two lines under moderate drought, severe drought and their well-watered controls, respectively. Transcription factors were enriched in both genotypic differentially expressed genes and specifically responsive genes of the tolerant line. It was speculated that the genotype-specific response of 20 transcription factors in the tolerance line and the sustained genotypically differential expression of 22 transcription factors might enhance tolerance to drought in maize. Our results provide new insight into maize drought tolerance-related regulation systems and provide gene resources for subsequent studies and drought tolerance improvement.

干旱是制约玉米生长与产量形成的主要非生物胁迫因素。解析玉米耐旱性的分子调控网络具有重要的理论与应用价值。本研究以一对耐旱性差异显著的玉米自交系为材料，在田间自然土壤干旱及充分供水条件下开展试验；同时采用RNA测序（RNA-Seq）技术分析二者的叶片转录组。总计，耐旱系与敏感系中分别有555个和2558个基因特异性响应干旱胁迫，且耐旱基因型中呈现出更强的正向调控倾向。此外，在中度干旱、重度干旱以及二者对应的充分供水对照条件下，两个自交系间分别有4700、4748、4403和4288个基因呈现差异表达。转录因子（Transcription Factor）在基因型间差异表达基因以及耐旱系的特异性响应基因中均显著富集。本研究推测，耐旱系中20个转录因子的基因型特异性响应，以及22个转录因子的持续性基因型间差异表达，可能协同提升玉米的耐旱性。本研究结果为解析玉米耐旱相关调控系统提供了新的见解，同时为后续相关研究及玉米耐旱性遗传改良提供了候选基因资源。